Separate Control Strategies Research Articles

Towards Practical Flow Sensing and Control via POD and LSE Based Low-Dimensional Tools

Low-dimensional methods including the Proper Orthogonal Decomposition (POD) and Linear Stochastic Estimation (LSE) have been applied to the flow between a backward facing ramp and an adjustable flap. A range of flap angles provide a flow which is incipiently separated and can be used to flesh out ideas for active feedback separation control strategies. The current study couples Particle Image Velocimetry (PIV) and multi-point wall pressure measurements using POD and LSE to estimate the full velocity field from the wall pressure alone. This technique yields a sufficiently accurate estimate of the velocity field that the incipient condition can be detected. The ability to estimate the state of the flow without inserting probes into the flow is important for the development of practical active feedback flow control strategies.

Species status and population genetic structure of grapevine eriophyoid mites

AbstractBud mite, blister mite (Colomerus vitis Pagenstecher), and rust mite (Calepitrimerus vitis Nalepa) (Acari: Eriophyoidae) are recognized grapevine pests. Much of the biology and ecology of these pests is poorly understood. We used two types of molecular markers to gain further insight into the breeding biology and population structure of these mites, using individuals collected from sites around south‐eastern Australia. Patterns of genetic variation observed using PCR‐RFLP of ITS 1 (Internal Transcribed Spacer 1) confirmed the separate species status of the rust mite, and resolved the species status of bud and blister mites, revealing two closely related but distinct species. Microsatellite markers revealed extensive genetic differentiation between bud mite populations and blister mite populations even at micro‐geographical levels, suggesting low movement in these species. The findings indicate that separate control strategies are needed against bud and blister mites, and that localized control strategies are likely to be effective given their limited dispersal.

Control of an EV drive with reduced unsprung mass

Traditionally, the motors used in electric vehicles as direct wheel drives were built entirely into the vehicle wheel; this, however, increases the weight of the wheel. The drive arrangement described here utilises a permanent magnet, brushless, axial field double-sided disc motor. This type of machine, particularly the double-sided stator configuration, is attractive because rotor misaligninents perpendicular to the motion of the drive shaft can be accommodated. In such an arrangement, the stators of the machine can be mounted onto the chassis of the car and the rotor is allowed two degrees of freedom (rotational and transverse), and thereby directly drives the road wheel. Hence, a reduction in the unsprung mass of the wheel drive is achieved. However, there is a drawback: since the wheel is perturbed by the road surface roughness effects, the rotor moves between the outer stator assemblies (transversely), and consequently induces torque pulsations in the machine. Two separate control strategies to eliminate the torque pulsations caused by the rotor perturbation are investigated: modulation of the input motor current, and instantaneous torque control using a variable structure controller. The experimental results in each case show that both control strategies are effective in eliminating the torque pulsations.

Acceleration feedback for control of a flexible manipulator arm

AbstractMany studies to date have dealt with control and modeling strategies for endpoint positioning of flexible manipulator arm systems, and some actual experiments have been documented in verification of developed methods. This article describes laboratory results for a single‐link flexible manipulator arm in which three separate control strategies are compared and contrasted. Namely, the control schemes compared are: compensation using classical root locus techniques with endpoint position feedback, a full state feedback, observer‐based design, and compensation using endpoint acceleration feedback. The last technique, designs using accelerometer feedback, has received very little attention to date, and results here indicate great promise for use in flexible manipulator control.